Representative spectra from the MC simulation, visualizing the effect of f_V in the final spectrum appearance and classification. A normal SN Ia and a 91T-like event are shown at maximum light with f_V ~ 1. Even at this 1:1 level, the CSM contamination is barely visible in the spectra. From objects that were classified as Ia-CSM we show two cases with f_V = 0.74 and 0.27. At lower flux ratios, it is not possible to distinguish the spectral features and the SNe were classified progressively as IInS and IIn. The spectra have been scaled by arbitrary constants for presentation purposes.